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 Post Posted: Sun Nov 21, 2010 9:16 pm 
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Location: Indiana
I recently picked up this standard bore block for next to nothing. I have heard the horror stories about these 400's, but am curious as to what others think before I possibly waste my money. This motor will be a circle track motor so filling the block won't be an option. Is it worth the time or should I stay with another 383-388 combo like I have now? Any help is appreciated.

Thanks, Dave
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 Post Posted: Sun Nov 21, 2010 10:10 pm 
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How these blocks hold up depends alot on how much compression and HP you are going to have. Anything over 10.5 to 1 compression is asking for trouble and I'd say that 600 HP would be a little more than I'd want to get from one.

I've got one of these blocks that isn't poured and it's survived now since way back in 1991 but it does have aftermarket billet steel caps on it, which I don't think is that much of a plus on a low HP engine. I just had them put on that block because I didn't know any better at the time.

So how much head and camshaft are you going to run in that thing?

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 Post Posted: Mon Nov 22, 2010 5:51 am 
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INT .358 .537 287° 256° 29° BTC 47° ABC 81° .026 99° 8 Uses 1.5 ratio on Intake & Exhaust.
EXH .371 .557 295° 264° 63° BBC 21° ATC .026 111°

Heads are RHS Pro Action 64cc with 200 runners

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 Post Posted: Mon Nov 22, 2010 8:48 am 
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My GM 400 based block is actually a 434 CID. It has a set of Brodix Track 1 heads with 76cc chambers, a piston with what appears to be a .100 DISH, not dome and it's a solid roller cam with 268* and 272* @.050 with .660 lift.

Are you limited on compression?

FYI, the 2 bolt block is actually stronger in the crank web section than the 4 bolt blocks are because the outer bolt locations weaken the web. I've got another 400 that I put 3 Milodon splayed caps on that is a spare that I'm saving for when the one I'm running now pukes.

You can run a standard GM "pink" 5.7 rod but you "might" have to do some machining on the inner rod bolt tops for cam clearance, especially on #6 cylinder ( I think that's the one). If you go with an Eagle stroker rod then they will most likely clear OK. On my engine I run a small base circle cam and a Carrillo stroker rod and I had to grind the end of the rod bolts off where they come through the top side of the connecting rod. Mind you that this is a 4 inch stroke engine though so with a stock 3.75 stroke this shouldn't be that much of a problem for you. I would still run the stroker rods though as you are going to use a solid flat tappet cam which is much larger in diameter than my roller cam.

When these engines are built with low compression they seem to hold up really well however I've had one blow a cylinder wall out and one cracked a cylinder because of too much. In other words, if you can't run pump gas in it then I'd consider it a potential grenade waiting to happen.

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 Post Posted: Mon Nov 22, 2010 6:09 pm 
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No there's no limit on compression. We can run gas or alky. Current setup was on gas (110) but considering maybe another route to keep the cost down. FYI the guy I got this from couldn't find any of the original main caps so I will probably have to get those anyway.

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 Post Posted: Mon Nov 22, 2010 6:27 pm 
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Like Ken said you need to be careful of what you do with that block..IMO I would do another 383.. Bump the compression up run some good parts in it and the most important part the right cam for what your doing...Rick can mabe help you on that....

Cyd walls are already thin on a 400 block and ring seal it questionable on them and you don't have the main caps... :-

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 Post Posted: Mon Nov 22, 2010 6:40 pm 
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Limit the bore to 4.145 if possible.


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 Post Posted: Mon Nov 22, 2010 7:06 pm 
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I've got 2 more good 350 4 bolt blocks in the shed. I'm starting to lean toward building another 383. The 388 I have now I burnt a couple pistons on and needs rebuilt or start fresh. I have all parts except set of pistons to do it. If aftermarket blocks weren't so expensive I'd go that route, but not in the budget now! [-(

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 Post Posted: Mon Nov 22, 2010 11:39 pm 
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The thing you need to do is figure out why you're burning pistons! So have you got a reason why that's happening?

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 Post Posted: Tue Nov 23, 2010 4:00 pm 
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Not positive, there was a couple things I found out of the norm, beginning with the valve train geometry which caused lift to be way off. Motor was way down on power of course, didn't take long to get pretty warm. Probably detonation was the worse case scenario. I'm used to running all my motors prior on alky, this one is on gas.

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